MOM6: Merge pull request #869 from nikizadehgfdl/nikizadeh_diag_decim…

…ation

- Available diags change due to NOAA-GFDL/MOM6@00f634b31

MOM6 commits:
- NOAA-GFDL/MOM6@dd7607d8a Merge pull request #905 from Hallberg-NOAA/rescale_Coriolis
- NOAA-GFDL/MOM6@833d9aeff Merge branch 'dev/gfdl' into rescale_Coriolis
- NOAA-GFDL/MOM6@aceda8f7a Merge pull request #906 from adcroft/travis-switch-to-mpich2
- NOAA-GFDL/MOM6@dc2e629f6 Travis: switch to mpich2
- NOAA-GFDL/MOM6@d3a57bc16 +Added dimensional rescaling of Coriolis parameter
- NOAA-GFDL/MOM6@d93b04798 Merge pull request #901 from navidcy/UpdatesDocEquations
- NOAA-GFDL/MOM6@00f634b31 Merge pull request #869 from nikizadehgfdl/nikizadeh_diag_decimation
- NOAA-GFDL/MOM6@f9f0327f8 undo changes in MOM_hor_visc.F90 doc
- NOAA-GFDL/MOM6@b42683d4b fixes geopotential gradient term in eqs and typo in \nabla def in notation.
- NOAA-GFDL/MOM6@8a979c3a5 fixes geopotential gradient term in governing eqs.
- NOAA-GFDL/MOM6@3ebcb6826 Merge pull request #896 from Hallberg-NOAA/coupling_options
- NOAA-GFDL/MOM6@9997f4149 Merge pull request #897 from nikizadehgfdl/nikizadehgfdl/fix_openmp_answers
- NOAA-GFDL/MOM6@8256a1172 fixes notation in mom_hor_visc module documentation
- NOAA-GFDL/MOM6@319ed39e1 adds parentheses in general-coordinate versions of temp and sal
- NOAA-GFDL/MOM6@37378cf72 adds parentheses in general-coordinate versions of temp and sal
- NOAA-GFDL/MOM6@d263de469 some more typos and a few nablas that were left unbolded
- NOAA-GFDL/MOM6@b8cdd7c6f fixes typo and adds Angus link
- NOAA-GFDL/MOM6@c19640baf changes vector notation and fixes typos
- NOAA-GFDL/MOM6@0a1a313b3 Correct thermo clock with update_ocean_model calls
- NOAA-GFDL/MOM6@1603ed98c Fix bug causing openmp answers change
- NOAA-GFDL/MOM6@b6fa3428e +Opt args to step_MOM can override DIABATIC_FIRST
- NOAA-GFDL/MOM6@0ff4c5b19 Trap or deal with instances when dt=0 in diabatic
- NOAA-GFDL/MOM6@9b7b127ba +New variants of safe_alloc_ptr & safe_alloc_alloc
- NOAA-GFDL/MOM6@8233da231 Diagnostics downsampling, shorten line more than 120 chars long
- NOAA-GFDL/MOM6@6d77f3921 Merge branch 'dev/gfdl' into nikizadeh_diag_decimation
- NOAA-GFDL/MOM6@48a491565 Merge branch 'nikizadehgfdl/fix_compile_generics' into nikizadeh_diag_decimation
- NOAA-GFDL/MOM6@9d7099fd8 Merge branch 'dev/gfdl' into nikizadeh_diag_decimation
- NOAA-GFDL/MOM6@c98fb7318 Diagnostics Downsample, implement Hallberg's suggestion
- NOAA-GFDL/MOM6@1cfc3841b Downsample Diagnostics, fix symmetric memory case
- NOAA-GFDL/MOM6@16fef4f69 Diagnostics downsampling, fix the issue for symmetric case
- NOAA-GFDL/MOM6@fe0c041f9 Diagnostics downsampling, implement suggestions in reviews
- NOAA-GFDL/MOM6@de8f1b66d Diag decimation, check the commensurate condition
- NOAA-GFDL/MOM6@861397c6d Merge branch 'dev/gfdl' into nikizadeh_diag_decimation
- NOAA-GFDL/MOM6@d748764c7 Diag decimation, fixed the decimated fields indices
- NOAA-GFDL/MOM6@0a3335fb0 Diag decimation prototype, decimation algorithm extension
- NOAA-GFDL/MOM6@2dd042a5c Diag decimation prototype, first attemp at general algorithm
- NOAA-GFDL/MOM6@373c23264 Diag decimation prototype, fix masks for non-native grids
- NOAA-GFDL/MOM6@5f3949fd7 Diag decimation prototype, fixed masks and cleanup
- NOAA-GFDL/MOM6@dfe674c5d Diag decimation prototype, aggregating methods
- NOAA-GFDL/MOM6@7e3d3685d Diag decimation prototype, fixing memory leaks
- NOAA-GFDL/MOM6@8802dd258 Diag decimation prototype, requesting in diag_table
- NOAA-GFDL/MOM6@d1b15c4a2 Diag decimation prototype, requesting in  diag_table
- NOAA-GFDL/MOM6@b9d714b49 Diag decimation prototype, works for native and _z
- NOAA-GFDL/MOM6@7c4adcb96 Diag decimation prototype, coarsening by a factor of 2
- NOAA-GFDL/MOM6@dcdd9ae1e Effort to decimate the diag output at runtime